Coexistence of valley polarization and Chern insulating states in MoS(2) monolayers with n-p codoping

The electronic and topological properties of MoS(2) monolayers with n-p codoping effect are investigated by using first-principles calculations. Two types of the doped Nb atoms play the roles of the p-type and n-type dopants, respectively. The n-p codoping is found inducing a large valley polarization, associated with the strong magnetization induced by the Nb dopants. Interestingly, the system simultaneously owns a perfect Chern insulating band gap opened exactly at the Fermi level. The nontrivial band gap comes from the lifting of the degeneracy of the d(xz) and d(yz) orbitals of Nb(2) atoms after the spin-orbit coupling is considered. Our work inspires exciting prospects to tune the novel properties of materials with n-p codoping effects.